Slice the chicken breast in half lengthways and then into 5-6mm (¼") thick strips diagonally across the breast.
Mix together the ingredients for the marinade and add the chicken, then allow this to sit whilst the remaining ingredients are prepared
Finely slice the garlic as finely as you can.
Peel and cut the ginger into batons as thinly as you can manage.
Finely slice one of the spring onions into 2-3mm (⅛") thick rings, shred the other two as thinly as you can and place the shredded spring onion in a bowl of cold water.
Toast the Szechuan peppercorns in a hot wok for 1-2 minutes and crush them in a pestle and mortar or spice grinder. If you want to refine the texture more, then pass it through a fine mesh sieve.
Toast the cashew nuts in a hot wok and set aside.
Mix together the ingredients for the sauce and set aside.
Get the wok almost smoking on a high heat and add the oil. Immediately add the garlic and ginger and stir fry for 30 seconds.
Add the chicken and marinade followed by the chilli flakes and Szechuan pepper and stir fry for 3-4 minutes.
Pour in the sauce, followed by the sliced spring onions and cashew nuts. Stir fry for a final 2-3 minutes.
Drain the shredded spring onions and serve on top of the stir fry.